In a camera module that uses a CCD (Charge Coupled Device) as an image capturing element, a phenomenon called “smear” occurs, for example. The smear is a phenomenon where, if intense light, such as the sun and an electric light, is included in a target subject, and enters into an image capturing element, a white strip-shaped part is generated in a captured image. The smear occurs due to a continuous overflow of charge in the CCD. Specifically, if a light receiving element (pixel) formed in the CCD receives intense light, the charge starts to overflow at a part of the light receiving element. As a result, in a charge exchange between the light receiving elements, the charge overflows in a chain reaction manner. Thus, the smear occurs.
In order to prevent such a smear, a camera module often includes a mechanical shutter. The mechanical shutter blocks the intense light, which causes the smear, before the smear is generated, so as to prevent an occurrence of the smear.
For example, Patent Literatures 1 and 2 disclose camera modules each of which includes a mechanical shutter. FIG. 7 is a cross-sectional view illustrating a camera module disclosed in Patent Literature 1. Meanwhile, FIG. 8 is a cross-sectional view illustrating a mechanical shutter disclosed in Patent Literature 2.
Specifically, as illustrated in FIG. 7, a camera module 110 disclosed in Patent Literature 1 has an arrangement in which a light-transmitting plate 112, an image capturing optical system 113, an image capturing element 114, a substrate 115, shutter blades 116 and 117, and the like are assembled together in a direction of an optical axis. Further, a shutter actuator 118 for electromagnetically driving the shutter blades 116 and 117 is provided lateral to the image capturing optical system 113.
On the other hand, as illustrated in FIG. 8, a mechanical shutter 120 for a camera module, disclosed in Patent Literature 2, has a depression section 121 in its central part. Further, drive mechanisms 126 and 127 for driving (i) a plurality of shutter blades 122 and 123, (ii) an aperture blade 124, and (iii) an auxiliary blade 125 are provided in such positions that the drive mechanism 126 is on one side of the depression section 121, and the drive mechanism 127 is on the other side. It should be noted that Patent Literature 2 does not clearly describe alignment of the members in the image capturing optical system, such as an image capturing lens.
Meanwhile, recently, there has been an increase in the number of cases where a camera module having an autofocus function is applied to a mobile phone. The autofocus function is realized by providing a camera module with a lens drive device. There are various types of the lens drive device, such as a VCM (Voice Coil Motor) type, a type for using a stepping motor, and a type for using a piezoelectric element. Such lens drive devices have been already on the market.
For example, Patent Literature 3 discloses a VCM type lens drive device. FIG. 9 is a cross-sectional view illustrating a lens drive device disclosed in Patent Literature 3. A lens drive device 200 illustrated in FIG. 9 includes a holder 202 that includes a lens 201 in its central part. A plate spring 203U is provided on the holder 202, and a plate spring 203L is provided under the holder 202. This arrangement supports the holder 202 so that the lens 201 moves in the direction of the optical axis.
Further, a coil 204 is fixed to a flange section of the holder 202. The coil 204 is held in a yoke 205. On an inner surface of the yoke 205, a permanent magnet 206 is provided so as to face the coil 204 with a space therebetween. Such an arrangement enables the lens drive device 200 to be driven by electromagnetic power.
Meanwhile, three projections 208 are formed on a base 207. When the lens drive device 200 is completed, each of the projection 208 supports the holder 202.
An opening 210 is formed in a central part of a cover 209 provided above the yoke 205, and another opening 211 is formed in a central part of the base 207. The openings 210 and 211 are formed so as to transmit light.
However, the conventional camera module has a problem, that is, in a case where both a mechanical shutter and a lens drive device are provided to the camera module, it is impossible to cause the camera module to be smaller and thinner at the same time.
Specifically, in a case where, in order to cause the camera module 110 having the mechanical shutter (as illustrated in FIG. 7) to have the autofocus function, the camera module is provided with a lens drive device, the lens drive device has to (i) include the permanent magnet and the like, and (ii) be provided in the vicinity of the image capturing optical system 113. Further, the shutter actuator 118 should be provided lateral to the lens drive device. As a result, a size (lateral width) of the lens drive device becomes large.
On the other hand, in order not to have such an increase in size of a camera module, there may be another structure in which the mechanical shutter and the lens drive device are simply stacked with each other. An example of such an arrangement may be a camera module in which the mechanical shutter illustrated in FIG. 8 and the lens drive device illustrated in FIG. 9 are simply stacked with each other. However, such stacking increases a thickness of the lens drive device illustrated in FIG. 9 by a thickness of the mechanical shutter illustrated in FIG. 8.
The demand for a smaller and thinner device has increasingly grown, particularly for a mobile phone having a camera. Along with the demand, there is almost no space for a shutter actuator to be provided lateral to a lens drive device. Furthermore, the stacking of the mechanical shutter and the lens drive device goes against the demand for a thinner device.